Prognostic value of circulating tumor cells in esophageal cancer

Abstract

Aim: To perform a meta-analysis of the related studies to assess whether circulating tumor cells (CTCs) can be used as a prognostic marker of esophageal cancer.

Methods: PubMed, Embase, Cochrane Library and references in relevant studies were searched to assess the prognostic relevance of CTCs in patients with esophageal cancer. The primary outcome assessed was overall survival (OS). The meta-analysis was performed using the random effects model, with hazard ratio (HR), risk ratio (RR) and 95% confidence intervals (95%CIs) as effect measures.

Results: Nine eligible studies were included involving a total of 911 esophageal cancer patients. Overall analyses revealed that CTCs-positivity predicted disease progression (HR = 2.77, 95%CI: 1.75-4.40, P < 0.0001) and reduced OS (HR = 2.67, 95%CI: 1.99-3.58, P < 0.00001). Further subgroup analyses demonstrated that CTCs-positive patients also had poor OS in different subsets. Moreover, CTCs-positivity was also significantly associated with TNM stage (RR = 1.48, 95%CI: 1.07-2.06, P = 0.02) and T stage (RR = 1.44, 95%CI: 1.13-1.84, P = 0.003) in esophageal cancer.

Conclusion: Detection of CTCs at baseline indicates poor prognosis in patients with esophageal cancer. However, this finding relies on data from observational studies and is potentially subject to selection bias. Prospective trials are warranted.

Keywords: Circulating tumor cells; Esophageal cancer; Meta-analysis; Prognosis.

Figure 1

Selection process for studies included in the meta-analysis.

Figure 2

Forest plots of the hazard ratios for overall survival. OS: Overall survival; IV: Inverse variance; df: Degrees of freedom.

Figure 3

Funnel plot of the studies on overall survival.

Figure 4

Forest plots of the hazard ratios for disease progression. HRs: Hazard Ratios; DFS: Disease-Free Survival; PFS: Progression-Free Survival; RFS: Relapse-Free Survival; IV: Inverse variance; df: degrees of freedom.

Figure 5

Forest plots of the RRs for clinicopathological characteristics. A: TNM stage; B: T stage; C: Histological differentiation. RRs: Risk Rataios; M-H: Mantel-Haenszel; df: Degrees of freedom.